Firing rate conversion means for automatic firearms



5 Sheets-Sheet 1 R. H. COLBY mm mm mm INVENTOR. EiBhuTfl-H [Zun Ji QJ FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS May 2, 1961 Filed May 5, 195a y 1961 R. H. COLBY 25982,]83

FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS Filed May 5, 1958 5 Sheets-Sheet 2 INVENTOR.

Rial-1111i H- E011 5 Sheets-Sheet 3 iill R. H. COLBY FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS May 2, 1961 Filed May 5, 1958 INVENTOR. Riuhu d H E|:|]iny IRE 23 m lmwh y 1961 R. H. COLBY 2,982,183

FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS Filed May 5, 1958 5 Sheets-Sheet 4 INVENTOR. Him bu rd H En Ely May 2, 1961 R. H. COLBY FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS Filed May 5, 1958 5 Sheets-Sheet 5 INVENTOR. Rink ma H- EH11,

FIRING RATE CONVERSION MEANS FOR AUTOMATIC FIREARMS Richard H. Colby, South Hadley, Mass, assignor to the United States of America as represented bythe Secreany of the Army i Filed May 5, 1958, Ser. No. 733,216

8 Claims. (Cl. 89-129) (Granted under Title '35, US. Code (1952), sec. 266) The invention described herein may be manufactured and-used'by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relatesto automatic recoil-operated guns and is more particularly directed to guns of this type vlhich can be fired at a high or low rate at the option of the operator. This application is a continuation-impart ofrthe application by Richard H. Colby for Dual Rate Machine Gun, Serial No. 577,903, filed April 12, 1956, and now abandoned.

The growing complexity of, modern warfare requires that every attempt be made to design weapons which can accomplish more than one type of mission. For example, it is highly desirable to be able to employ the same machine gun against-ground personnel as well as against low-flying aircraft. However, in order to assure eiiicient operation against either of these two types of targets, the gun must be capable of reliable operation at both a low and a high rate of fire and must also possess suitablemeans for rapidly converting the gun from operation atone rate to the other. While various prior'art weapons are capable of this dual operation, such feature has usually been-accomplished through suitable mechanism for incrementally varying the rate of travel imparted to the recoiling parts. This is generally accomplished by sometype of hydraulic, pneumatic, or resilient device which'can be set to absorb more or less of'the energy imparted to-the recoiling parts of the gun. While successful variation in the rate of travel of the recoiling parts has been achieved in the prior alt, considerable difficulty has been experienced in rapidly converting from one extreme rate of fire to the other without detrimental efiecton the reliability and uniformity of operation.

Accordingly, it is an object of this invention to provide improved means for rendering "an automatic recoil-op erated gun capable of selective conversion between uniform high and'low rates of fire. g

I It is a further object of the present invention to provide an automatic recoil-operated gun wherein the operation thereofcan be readily convertedbetween a high and a low rate of fire without providing'a corresponding change in the rate of travel of the recoiling parts.

Still another object of this invention lies in the pro vision" of an automatic recoil-operated gun' wherein the operation the'ieofcan be readily converted between a high and low rate of fire simply through the selective A more s'peciii'c'obj ect of this invention is to provide a manuallyoperated selector device for effecting the direct conversion of an'automatic recoil-operated gun between 2,982,183 ratented a'y 2, 196% a description of a preferred embodment as shown in the accompanying drawings in'which:

Fig. 1 is a longitudinal sectional view of the rear portion'of the gun with the recoiling parts shown'in the battery position; a

Fig. 2 is a forward extension of Fig. 1 with the recoil conversion mechanism shown in the position for securing short recoil operation of the gun and being partially brokenaway to more clearly show the relationship of I the component parts; I v k Fig. 3 is a view similar to Fig. l but with the recoiling parts shown shortly after the bolt has been unlocked" from the barrel extension'and immediately prior tothe termination of the short recoil movement of the barrel;

Fig. 4 is" a forward extension of Fig. 3 sim'ilar to Fig; 2 but showing the means for halting the rearward movemerit of the barrel toobtain' short recoil operation of the partial section to'show the recoiling parts at the conclusion of long recoil travel and to show the respective means for'separately returning the bolt and the barrel to battery positions;

Fig. 8- is a cross-sectional view taken alongline 8--8 ofFig.7; x V V Y Fig. 9 is a cross-sectional view taken along'line.9--'- ofFig.7'

9 p Fig. 10 is a cross-sectional viewtaken.along.line.1 0 10 ofFig. 2 to show the engagement of the lugson the barrel extension with the internal lugsofthe recoil control ring for effecting short recoil operation of the gun and also showing in phantom the separatev housings for the respective bolt and barrel counterrecoil springs;

Fig. 11 is a view similar to that of Fig. 10 but with the mechanism for converting the recoil operation of the gun shown in the long recoil position and also showing the means for imparting the movement of the selector lever to the recoil control ring; p

Fig. 12 is a cross-sectional view taken along'line 12-12 of Fig.v 6 with the recoil conversion mechanism in the Fig. 13 is a cross-sectionalview taken alongline extreme high and low rates of fire without the necessity for operating'tlre gun through any intermediate ratesof' 1 The specific nature 'of the inventioni as' well a's othe'r of Fig. 6 to show the relationship between the stopshoul der on the barrel and the lugs on the barrel'bufier sleeve when the selector has been rotated to the; position for' effecting long recoil operation of the gun and also to show *themeansffor securing thebolt and barrel counterrecoil barrel l8 h avingarl.v extension Zt) threadably sec ured tothe rear end'thereof asshown at ZI'andfsec'nreIy; locked together by a threaded'stud 22.. Theforward end of receiver 14 is exteriorly threaded as shown'at 23in order to permit mounting. of the gun; to any suitable fixed sup port 25. Longitudinal rib'si 3 3 are provided on opposite I, sides'ofbarrel'extension 20'a's shownin nigi'jand are sectional view taken along adapted to slidably engage in correspondingly positioned rectangular ways 34 longitudinally formed along the interior wall surfaces of receiver 14.

1 Bolt assembly 16 essentially comprises a body 24. and

a head 26 having a plurality of spaced apart interrupted.

rings 28 at the forward end thereof arranged for mating engagement with similarly formed locking segments 30 formed within the rear end of barrel extension 20. Bolt body 24 is provided with outwardly projecting rectangular ribs 32 on either side thereof adapted to slidably engage in receiver ways 34. The underside of bolt body 24 includes a notch 36 adapted to beengaged by the free end of a longitudinal sear lever 38 pivotally mounted at its opposite end in a suitable housing 40 fixedly secured to the floor of receiver 14. A spring 42 is located between the bottom of housing 40 and the underside of sear lever 38 to provide the bias necessary to continually urge such lever into position to engage in notch 36 for retaining bolt body24 in the fully recoiled position. Sear lever 38 is suitably connected to a release mechanism (not shown} which is arranged to be actuated by the movement of barrel 18 into the battery position in a manner well known in the art. l

Bolt head 26 is provided with oppositely projecting cylindrical studs 44 terminating in substantially rectangular end portions 46 arranged to slidably engage in receiver ways 34 subsequent to the unlocking thereof from barrel extension 20 duringshort recoil operation of the gun. However, inasmuch as bolt head 26 is not rotated=relative to bolt body 24 when the gun is set for long recoil operation, a similar rectangular way 48 but of lesser depth is longitudinally disposed along each of the opposite interior wall surfaces of receiver 14 above one of ways 34 and below'the other to slidably receive end portions 46 of bolt head studs 44. A substantially rectangular passage 50 is formed in both sides of receiver 14 to connect ways 43 and 34 and thereby provide a passageway for end portions 46 as bolthead 26 is rotated to unlock from the seared bolt body 24 when the gun is set for long recoil operation.

- As best shown in Fig. 8, a camming insert 52 is pivotally mounted in a bifurcated bracket 53 projecting outwardly from the right side of receiver 14 and is arranged to normally extend into the interior of receiver 14 through a transverse slot 55 therein. Insert 52 is provided with a pair of adjacent longitudinal holes 57 therethrough arranged to selectively receive a pin 59 whose opposite ends extend into suitable openings in bracket 53. When pin 59 engages the outer one of holes 57, insert 52 is positioned to project into the interior of receiver 14 and thereby serves to cam bolt head 26 out of locked engage ment with barrel extension 20 during the short recoil movement of bolt assembly 16. However, when long reco'il operation of the gun is desired, pin 59 is withdrawn 2 and insert 52 is pivoted outwardly to align the inner one of holes :57 with the pin openings in bracket 53. Pin 4 59 is then replaced to lock camming insert 52 in this pivoted position whereby bolt head 26 remains locked to barfel extension 20 during the entire recoil travel of bolt assembly, 16 and consequently increases theftime intervalbetweeneach cycle of operation .of the gun. A suit able buffer assembly 54 is provided in therear end of receiver 14 to cushion and halt. the recoiling travel of bolt assembly lfi. V j v 'lhetorward endof receiver 14 is counterbored as showriat 56 and. a cylindrical .housing 58 is rotatably mounted therein and retained against forward 4 movement byja'barr'el'support collar "60 threadably secured toQthe frontmend .ofreceiver 14. Collar .60is formed with a forwardl'yltapering portion 62 having an axial bore 64 thertliro'ugli in which barrel 18 is slidably disposed for recipiocal"[longitudinal movement. Housing 58 is atrangeditoi contain the springassemblies required to con-.

The forward half of barrel 18 is of slightly greater diameter than the rear half thereof and consequently forms an annular shoulder 66 for a purpose to be hereafter shown. A plurality of longitudinal splines 68 are circumferentially spaced about the periphery of barrel 18 so as to terminate slightly rearwardly of shoulder 66. The height of splines 68 does not exceed the larger diameter of barrel 18 and therefore permits passage thereof through bore 64 of collar 60 during long recoil operation of the gun. Barrel 18 is also provided with a relatively shallow groove 70 extending longitudinally along the top thereof so as to receive the depending nose of a latch 72 pivotally secured to the forward end of receiver 14 and extending through a suitable vertical opening 73 therein. A spring 74 normally biases the nose of latch 72 into groove 78 thereby preventing any rotation of barrel 18 relative to receiver 14. The breech end of barrel 18 is longitudinally cut away as best shown at 76 in Fig. 5 and the cylindrical configuration of barrel extension 20. is similarly cut away at the top thereof to the extent necessary to bring the opposing free ends formed thereby into transverse alignment with the flattened portion 76 of barrel 18 asbest shown in Figs. 10 and 11. As a result of the foregoing construction, barrel 18 and barrel extension 20 are adapted to reciprocate without interference by the underside of a cartridge feed tray 78 fixedly mounted into the top of receiver 14. 1

Barrel extension 20 extends forwardly beyond the area of locking engagement with barrel 18 to form a reduced diameter section 80 having a plurality of spaced apart, radially dis-posed lugs 82 projecting outwardly from the extreme forward end thereof. Correspondingly positioned lugs 84 are provided about the interior bore surface of a recoil control ring 86 which is slidably disposed within barrel control housing 58 for reciprocal longitudinal movement. However, rotation of ring 86 in housing 58 is prevented by a pair of pins 88 which are fixedly secured in opposite sides of ring 86 and project outwardly therefrom to extend into correspondingly disposed longitudinal slots 90 within housing 58 as shown in Figs. 10 and ll.

Thus, when the rotation of housing 58. is imparted to ring 86 in a manner to be hereinafter shown, lugs 84 therein are either positioned in axial alignment with lugs 82 on barrel extension 20 or are disposed therebetween depending upon the direction in which housing 58 has been rotated. In the first mentioned position, the recoil travel ofrbarrel extension 20 is imparted to ring 86 by the engagement between lugs 82 and 84 while in the second mentioned position lugs 82 pass between lugs 84 to permit the long recoil travel of barrel 18 and the extension 20 thereon.

Barrel control housing 58 is provided with an internal flange 92 arranged for contact by a forwardly facing annular shoulder 93 on the exterior of ring 86 for halting the forward movement thereof. Flange 92 is of sufficient depth to receive the projectingthreaded end 94 of a screw 96 slidably disposed in a counterbored hole 102 extending vertically through a lever 99. As best shown in Figs. 2 and 10, lever 99 is a part of a selector assembly 98 and is provided with a knob portion 160 at the upperend thereof. A spring 104 is arranged to be compressed between the head portionof screw 96 and an annular shoulder 106 formed in hole 102 and thereby serves to normally urge the underside of selector lever 99 into contact with the exterior surface of barrel control housing 58. Receiver 14 is provided with a transverseslot 108 which is substantially equivalent in width to the diameter of screw .96 and terminates. at. either end thereof in enlarged semicircular openings 110 arranged to slidably receive the cylindrical lower end of selector lever 99. Thus, in order to rotate lever .99 between the settings for short and long recoil operationof. the gun, knob. portion. is raised against the bias of spring 104 out of engagement with one of the semicircular ends in receiver 14 and is then rotated into alignment barrel buffer collar 116.

rotational movement relative to receiver '1 Assembly 14s includesia cylinder 152; slidably'di spo sed in housing 146 on .a fixedgu-iderod'154 extending' V betweenthe front and rear ends of lIOtising 1 46f The. 'fro nt end of cylinder 152 is 'f ormedto' provide-afront '14 andfits intoa suitabl on the rifg'htside'ofibarrel extension 2 'j-r'ecoilmovement of barrel 1 nd sufiicient elierg'yisaccumulat y these parts 'tdthe battery po's' .5 with the other semicircular end 110 forengagementtherein upon being released. a

. Barrel control housing'58 is providedwith an annular 1 retainer 112 threadably secured into therear endthereof and arranged to provide a s ea t for; the rear end of a barrel recoil-spring -114 which surrounds barrel 18 and its extension. 20 and normally biases recoil control ring =86 forwardly against the rear surface of flange 92 in barrel control housing 58. e

A barrel bufier collar, 116 is s'lidably disposed within barrel control housing 58 for contact with the forward face of flange 92. Thelforward end of housing 58 is provided with an exteriorly threaded-annular barrel buffer retainer 118 having a counterbored opening 1-20therelocated longitudinal slots 130 formed into barrel bufier Thus, pins 126 I serve to transmit rotational movement of barrel contro housing 58 to the barrel buffer sleeve 124. I

sleeve 124 from the rear end thereof.

The forward end of sleeve 124 is provided .with an exterior annular flange 132 arranged to slidably extend into counterbored opening 120 for contact with shoulder 122therein. A plurality 'of spacedv apart lugs l34gare radially disposed about the interior peripheryof sleeve 124 adjacent theforward end thereof and are arranged during short recoil operation of the gunfor. contactwith the rear ends of splines 68 to assistin halting the recoil movement of barrel 18. Such bufiing action is prefer- Qably accomplished through the snubbing action produced between an inner and an outer set of ring springs 188' and 136,. respectively, which are s-lidably mountedon barrel buffer sleeve 124 between flange 132 thereon and The front and rear ends of receiver 14 are each pro- 'vided'with a pair of oppositely disposed outwardly ex-U tending mounting lugs 140, As best shown'in Figs. 8 and 13, each of; lugs 140 is of susbtantailly rectangular configuration and is rectangularly slotted asindicate'd at 142 to transversely receive a similarly formed mounting stud 144 extending longitudinally i'from fthe front and'fthe rear 'endsof' a tubular housing "146 forming a component 7 part of a barrel counterrecoil spring assembly ,145 "posi tioned on the right; side of receiver 14, A headed pin seat 156101 a spring 158. Atransversely rojectingi'lug ii 1:8 gun is set for short recoil operation, the return of barrel -18 to the battery position 'is accomplished by recoil spring 114 and'ring springs 136 and 138 before counterrecoil spring assembly has been actuated to any appreciable extent.

In order to operate the gun in short recoil, camming .insert 52 is pivoted into the interior of receiver 14 so circular-opening 1111 at the opposite end-of slot 108, as

shown in Fig. '10, in the manner hereinbefore described. This rotative movement of selector lever 99 is transmitted to barrel control housing 58 by screw 96 and the rotation of housing 58 is in turn transmitted to recoil control ring 86 through pins 88. In the short recoil position of ring 86, lugs 84 therein are positioned in respective axial alignment with lugs 82 onthe forward end of barrel extension 20. At the same time, the rotation of barrel controlhousing 58 also serves to rotate barrelbuffer sleeve '124 and bring lugs 134 therein into axial alignment with the rear ends of splines 68 on barrel Uponthe firing of a cartridge, bolt assembly 16, barrel.

extension 20 and barrel 18 recoil asa unit until roller stud-44 on the right hand side of bolthead 26 strikes camming insert 52 andis' rotated out of locking engagement with barrel extension 20, as shown in Fig. 3. As barrel extension 20 begins to recoil, lugs 82 at the forwardend thereof engage lugs 84 withinrecoil control ring 86 and impart a corresponding rearwardmove-l ment thereto which compresses spring 114 to eventually haltthe recoil movement of the barrel assembly. During the recoil movement'ofthe'barrel assembly, the rear ends of splines 68. on barrel 18 contact lugs 134 within the interior of barrel bufier sleeve 12 4 and impart limited recoil .movement'thereto. Inasmuch as springs 136 and i 138 are seated against collar 116 which'is fixed against rearward movement due to the abutment'thereof with annular flange 92 in barrel control housing 58,.the re- .sulting snubbing action of ring springs 136 and 138 not a ceiver ways 34 and'compress counterrecoil spring assembly 147, as shown in Fig.;7, so that'when the recoil move- Qment of boltassembly is finally halted by buffer assembly .149 extend's vertically through "each lug 140an'd stud 1'44 I assembled thereto to releasjably'lock housing 146 against atthe rear end of cyIinderQ'ISZ extends.througha suitable longitudinal 105 1 2 ,aijoiig; th side or receiy'e'r 54, the energy accumulatedbysprin'g 158 is suflicient' to return, the ;bolt assembly 16 'to the battery position thereof. jThe final locking movement of "bolt head-26 during movement into battery position is,- of course, ef fected by the inertiamass of the-forwardly moving bolt Ibody24. i

In order to convert the gun to long recoil operation, camming insert 52is pivoted -to,;the position shownin Figs. Sand 14 andselector leverassernbly- 98 ispivoted to the position shown in- Fig. 11. En-this position of vselec-= 1 1 torjli etl99,, -recoil control-ring 86: ha's been rotated so that lugs 84 therein will permit thepassage therebetween of lugs 82011 the forward'endof barrel extension':.2t). .Thisrotati'on of recoilcontrol ring 86also servesto rotate 1,;barrl1buffer sleeve 124 sofas to positionlugs .84- therein out of the path ofimovement of splines 68 on barrel 18. f I f .lTlllJS, uponrecoil movement of bolt assembly 16inresponseto-the firingof a cartridge in barrel 18, the locking engagement between *bolt head .26. and j ba'rrelvextension20 will continue durin'gkthe; .entire recoil move- -rnent thereof The recoil energyof bolt assembly-16hr {considfitsblyereduced as shoulder 66Jo n barrel 18- contacts'lugs 134 within barrelbufier sleeve 124 immediately prior-to contact of bolt assembly l fi with butter assem- --bly 54 and produces :a' snubbing. action between ring I I springs 136 and 138. Roller studs 44 onbolthead 26am I I arrangedt travel in [receiver ways 48 while r'ibs' 32 on bolthody, 24 simultaneously travel in waysf34g 1 when bolt assembly 16 strikes buffer assembly 54 and begins:

the counterrecoil travel ithereot}. sear lever;38 engages sear notch 36 in the underside of bolt body Maud prevents theforward movement thereof. However; bolt, head 26 continues to counterrecoil together with barrel I 18 and, indoing so is rotatedto unlock from barrel ex I tension. so that roller studs 44 on bolthead Zipass I through passages 5 0 in=, the, opposite sides ofreceiver 14:

., and cause rectangular ends 46to engage in receiver ways I I 2:4.- Barrel I8 is returned to battery-position under-the I I I urging of. ring, springs: 153.6 and, 138 and; of counterrecoil 7 :springassembly 145 and at. the conclusion of such move 1 I mentsear lever 38 is actuated by means (not shown) to; I 1 release bolt; assembly 16 therefrom for return to battery I position :under. the urging of con I bly 147 It is apparentthat this considerably longer rccOiI and I counterrecoil. movement of barrel 18 requires a much;

p longer firing cycle and therefore provides :an appreciable 1 I I reduction in-theratet-of fire :of the gun incomparison to I that encountered during the'short recoil operation. Selec- =tionbetween these two rates of fire can be easily andz :,:rapidly= effected merely throughthe proper positioning otcarnrning insert 5,2 andthe'manipulationofselector- I I lever assembly 98. Thus, in the event a change of targets requires a'change in the firing rate of the gun, the new I .rate can be immediatelycbtained without; the necessity; I I I for gradually bridging the appreciableigap between these I I I I itwo ratesof fire -As a result of such rapid conversion "between the low and high rates of fire,zthe;unreliable and g I erratic operation generally found tooccur in thelpriorc art during a gradual attainment of the minimum or maximurnrate of fire is effectively eliminated.

, Although a particular embodiment ofthe invention has I been. described in detail herein, .it. is evident that many variations may be devised within the spirit and scope: I

1 thereof and the following claims are intended to include. I

such variations. I

i 1. In a recoil operated firearm having a receiver, a recoiling barrel, an extension fixedly secured to the breech end of the barrel, a bolt slidably mounted in-the receiver for reciprocal movement between recoil and battery positions, and means on the barrel extension for releasably locking the bolt theretoforjoint recoil rnovement, the combination of, a plurality of outwardly projecting lugsradiallyfspaced about the forward end of the barrel extension, a longitudinally slidable' recoilfcontrol ring rotatably disposed in the receiver to encircle the barrel extension forwardly of the bolt locking means thereon, saidrihg having a plurality of projecting lugs radially disposed abouttheinner periphery thereof in spaced correspondence with said barrel extcnsion' lug's,

arecoil spring surrounding the barrel extension to seat against said recoil control ring "and resist the rearward movement thereof,*selectormeansfor rotating said recoil control ring prior to the dis'charg'e of the firearm;to

positionsaid lugs thereon into and out of the'recoil p'ath i of 'said 'barrel extension lugs', and cam; means pivotally mounted in the receiver for movement into and out of the path of the bolt, said recoil spring being thereby utilized to haltthe recoil movement of the barrel during the continued recoil movement of the bolt only when said recoilcontrol ring lugs are positioned-forcontact with said barrel extension lugs and said cammieans-is posis L: tioned to=unlock the 12011: from the barrelj'extensio'n. 2. In a recoil operated'firearrn, the combination of a recoilingbarrel; an extension fixedly seciired tothe breech end of said barrel, a bolt slidably mounted in said receiverfor reciprocalmoven ent between recoil and batterypositions, meansonsaid barrel extension for renterrecoil spring assem;:

, rnent, .azplnrality ,of outwardly projecting lugs radially "spacedaboutthelforward endof said barrel extension, a

l cylindrical housing rotatablydisposed? in the forward end 1 ;of said receiver a recoilcontrol ring siidably disposed in I said housing to encircle said barrel extension forwardly I i ofzsaid bolt-lockingmeans thereon; said ring having. a

I plurality of projecting lugs radially disposed about ;the I I inner periphery thereof inspaced'correspondence with: 10- said barrel extension lugs, a recoil spring surrounding said barrel extensinn to seat] against said recoil control 3 ring and resist the rearwardmoveme'nt thereof, selector I means, for rotating said cylindrical housing in either I I direction, means for connecting said recoil control: ring to said housing in one; directionpositions said lags on saidmovement of said; barrel .duringthe continued recoil control ring lug'sou'toi the pathof said .barrelextension lugs,:spline means .on the exterior periphery :of said barrel, buffer means slidably disposed in said cylindrical when saidgrecoil control ring lugs are positioned for. en-;

I boltifrom s'aid'barrel extension;

'3. In arecoil operated firearm: having a receiver; a 3 recoiling barrel anextensio-n fixedly secured to the breech I I a boltslidably mountedinthe receiver I for reci'procal movement between battery andrecoil pos'iend of the: ban

tions, and means on the barrel extension for releasably locking the bolt thereto for joint recoil movement, the imtprovernent of means for. converting thefirearm between fast and'slow ratesjof fire comprising, in combination a plurality of outwardly projecting lugs radially spaced about the forward end of the barrel extension, a cylindrical housing rotatably' disposed in the forward end of the receiver, a recoil controiring slidably disposed in said housing to encircle the barrelextension forwardly of the bolt lockin'grmeans thereon, said ring having a plurality of projecting lugsdisposed ,about the inner periphery thereof in spaced; correspondence with said barrel extenrearward movement; thereof; a longitudinally slidable sleeve rotatabl'y disposed in said cylindrical i-rousing forwardly 015 said recoilcontrol ring therein, a pluralityof pro of I nderingsaidIcam said recoil Ednrotation theree said housing for rotatiomtherewith whereby rotation of I ring for engagement with said lugs on saidibarrel .exten- I 1 sion to compress said recoil spring for halting the recoil I I movement I of said bolt and whereby rotation I of said I housing in the opposite: direction positions saidrecoil I housingzforw ardly of said recoil control ring therein for engagement by said spline means on s'aid-barrel to assist I said" recoil spring in haltingthe recoil movement of said I barrel, and cam means: pivotally mounted inthe receiver I for movement into'and out of: the recoil path of said. e

bolt, said recoil springand: said :bufier' means beingi thereby utilized to-halt the recoil movement of said barrel during the, continued recoil'movement' er said bolt only. 1 I

I I gagement by said barrel'extension lugs, said bulfer'means' I is positioned lei-engagement by saidsplin'e means on said I 1 barrel, and said cam mcansgispositioned'to unlock said I sionlugs, a recoil spring surrounding the barrel extension '55 to seat againstfsaidfrecoil control ring and oppose the aesaiss 9 on the barrel extension and said splines on the barrel and thereby permit uninterrupted joint recoil movement of the barrel and bolt\when said cam means is rendered inopeiriative whereby the firearm is operated at a slow rate e.

4. The combination defined in claim 3 including resilient means for counter-recoiling the barrel and the bolt into battery positions when said selector means is positioned to permit uninterrupted joint recoil movement thereof, said resilient means comprising a tubular housing fixedly secured to each side of the receiver, a guide rod extending between opposite ends of each of said tubular housings, a cylinder slidably mounted on said guide rod, a spring seated in said cylinder to oppose rearward movement thereof, and a fixed lug adjacent the rear end .of each of said housings projecting into the receiver, one

of said lugs engageable with the bolt to impart forward movement thereto, and the other of said lugs engageable with the barrel extension to impart corresponding forward movement thereto. 5

5. The combination defined 'in claim 3 wherein said cam means for unlocking the bolt from the barrel extension comprises a bracket fixedly secured to one side of exterior surface of the receiver, a camming insert pivotally mounted to said bracket and having an inner and an outer longitudinal hole therethrough, and a replaceable pin extending through said bracket and one of said holes in said camming insert whereby the engagement of said pin in said outer hole therein positions said insert to project into the interior of the receiver for rotating the recoiling bolt out of locked engagement with the barrel extension while the engagement of said pin in said inner hole positions said insert outwardly of the recoil path of the bolt to permit uninterrupted recoil movement thereof jointly with the barrel.

6. In a recoil operated firearm having a receiver, a recoiling barrel, an extension fixedly secured to the breech end of the barrel, a bolt. slidably mounted in the receiver for reciprocal movement between battery and rea coil positions, and means on the barrel extension for releasably locking the bolt thereto for joint recoil movement, the improvement of means for selectively convert- I ing the firearm between short recoil operation wherein the recoil movement of the barrel is limited to a distance slightly less than the length of the cartridge to be fired therein and long recoil operation wherein the recoil movement of the barrel is equivalent to that of the bolt and is greater than the length of the cartridge, comprising a cylindrical housing rotatably disposed in the forward end of the receiver and having a longitudinal bore therethrough for passage of the barrel and barrel extension, 2, recoil control ring slidably disposed in said housing to encircle the barrel extension forwardly of the boltv locking means thereon, a plurality of outwardly projecting lugs radially spaced about the'forward end of the barrel extension, a plurality of correspondingly spaced lugs disposed about the inner periphery of said recoil control ring, a recoil spring'surroundingthe barrel extension and seated against the rear face of said ring to oppose rearward movement thereof, a circular flange disposed in the interior of said cylindrical housing to block forward movement of said recoil control ring, a

collar fixedly secured within the interior of said cylindrical housing forwardly of said circular flange therein to encircle the barrel forwardly of said .recoil spring; ,a sleeve disposed in said housing with the rearend, thereof n y jnslidable': engagement with said collar, an annular rel0 tainer fixedly secured in the forward end of said housing to block forward movement of said sleeve therein, said sleeve having an annular shoulder formed about the exterior of the forward end thereof, an inner and outer ring spring surrounding said sleeve between said annular shoulder thereon and said collar for opposing rearward movement thereof, a plurality of projecting lugs radially spaced about the inner periphery of said sleeve, a plurality of longitudinally extending splines circumferentially disposed about the exterior periphery of the barrel in spaced correspondence with said lugs on said sleeve, cam means pivotally mounted in the receiver for unlocking the bolt from the barrel extension during the recoil movement thereof, means for rendering said cam means inoperative, said recoil spring and said ring springs being thereby utilized to halt the recoil movement of the barrel for effecting short recoil operation of the firearm, pi-n means connecting said recoil control ring and said sleeve to said housing for rotation therewith, an exteriorly projecting selector lever fixedly secured to said cylindrical housing for imparting rotation thereto, means for latching said selector lever in a first position wherein said recoil control ring lugs are in the recoil path of said barrel extension lugs and said lugs on said sleeve are in the recoil path of said barrel splines to halt the recoil movement of the barrel during the continued recoil movement of the bolt and thereby provide short recoil operation of the firearm, and means for latching said selector lever in a second position wherein said recoil control ring lugs and said lugs in said sleeve permit uninterrupted joint recoil movement of the barrel and bolt when said cam means for unlocking the bolt from the barrel is inoperative and thereby provide long recoil operation of the firearm.

7. The combination defined in claim 6 including an annular shoulder on the barrel forwardly of said longitudinal splines thereon for engaging said lugs within said sleeve to reduce the recoil energy of the bolt upon the References Cited in the file of this patent UNITED STATES PATENTS 958,545 Ross May 17,1910 1,802,422 Heinemann Apr. 28, 1931 2,115,526 Holek Apr. 26,1938 2,470,158 Gazda May 17, 1949 a 2,782,688 Leek et al. Feb. 26, 1951 FOREIGN PATENTS Y 1 r Y 25,838 Great Britain; 1910 559,586, Great Britain Feb. 25, 1944 conclusion of the long recoil movement thereof. I

8. The combination defined in claim 6 wherein the receiver is provided with a transverse slot terminating in enlarged ends, said selector lever is provided with a vertical counterbored hole, and said means for latching said selector member comprises a screw having an enlarged head and slidably disposed in said counterbored hole with the threaded end thereof projecting through said transverse slot in the receiver to engage in said cylindrical housing, and spring means seated between the bottom of said counterbored hole and said enlarged head on said screw to normally urge said lever into engagement with I one of said enlarged ends of said transverse slotin the receiver, said lever being convertible from one enlarged end'of said transverse slot to the other for rotating said cylindrical housing accordingly.

883,448 France Mar. 22, 1943 

